CD44 and neoplasm: In support, the LAPC9 model harbors tumorigenic subpopulations that can be prospectively enriched using CD44+ and CD44+α2β1+ profiles as well as the SP and ALDH assays with the CD44+α2β1+ subpopulation being the most tumorigenic (i.e., ∼1 tumor-initiating cell in every 20 cells; Table 2).